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   1  <?php
   2  /**
   3   * Class used internally by Diff to actually compute the diffs.
   4   *
   5   * This class uses the xdiff PECL package (http://pecl.php.net/package/xdiff)
   6   * to compute the differences between the two input arrays.
   7   *
   8   * $Horde: framework/Text_Diff/Diff/Engine/xdiff.php,v 1.6 2008/01/04 10:07:50 jan Exp $
   9   *
  10   * Copyright 2004-2008 The Horde Project (http://www.horde.org/)
  11   *
  12   * See the enclosed file COPYING for license information (LGPL). If you did
  13   * not receive this file, see http://opensource.org/licenses/lgpl-license.php.
  14   *
  15   * @author  Jon Parise <jon@horde.org>
  16   * @package Text_Diff
  17   */
  18  class Text_Diff_Engine_xdiff {
  19  
  20      /**
  21       */
  22      function diff($from_lines, $to_lines)
  23      {
  24          array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
  25          array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
  26  
  27          /* Convert the two input arrays into strings for xdiff processing. */
  28          $from_string = implode("\n", $from_lines);
  29          $to_string = implode("\n", $to_lines);
  30  
  31          /* Diff the two strings and convert the result to an array. */
  32          $diff = xdiff_string_diff($from_string, $to_string, count($to_lines));
  33          $diff = explode("\n", $diff);
  34  
  35          /* Walk through the diff one line at a time.  We build the $edits
  36           * array of diff operations by reading the first character of the
  37           * xdiff output (which is in the "unified diff" format).
  38           *
  39           * Note that we don't have enough information to detect "changed"
  40           * lines using this approach, so we can't add Text_Diff_Op_changed
  41           * instances to the $edits array.  The result is still perfectly
  42           * valid, albeit a little less descriptive and efficient. */
  43          $edits = array();
  44          foreach ($diff as $line) {
  45              switch ($line[0]) {
  46              case ' ':
  47                  $edits[] = &new Text_Diff_Op_copy(array(substr($line, 1)));
  48                  break;
  49  
  50              case '+':
  51                  $edits[] = &new Text_Diff_Op_add(array(substr($line, 1)));
  52                  break;
  53  
  54              case '-':
  55                  $edits[] = &new Text_Diff_Op_delete(array(substr($line, 1)));
  56                  break;
  57              }
  58          }
  59  
  60          return $edits;
  61      }
  62  
  63  }